The interaction of NAD and the complex of borate with NAD, NADB, with liver alcohol and other dehydrogenases will be investigated using stopped-flow and temperature jump spectrophotometry, in order to determine the cause of the noncompetitive nature of borate inhibition of these enzymes, and in order to explore the nature of the NAD binding site on the enzyme. Also, an attempt is to be made at isolating and characterizing the enzyme from yeast which catalyzes the conversion of NADHX to NADH, in order to understand the role of this enzyme in the living cell. Possible roles of NADHX in the living cell will be investigated by studying the chemical properties of NADHX and its interaction with dehydrogenases.